This invention relates to a communication network over which data is transmitted, and more particularly to a network having master and slave network nodes.
The communication network of the present invention is particularly well suited for operation in a hostile electromagnetic environment, such as in an automobile. Heretofore, communication systems used to couple data between components in automobiles have relied on DC coupling of the signals to the communication network. Many of the systems in an automobile, for example headlights and electric motors to control power windows, produce sharp transient spikes whenever they are turned on or off. These transients often interfere with data being passed along the communication network between the automobile's computer(s) and the devices controlled by the computer(s). In order to deal with such problems, the prior art systems typically transmit the data very slowly, and may use redundant transmission and error checking techniques to overcome the effects of transient voltage spikes and other electromagnetic interference. Alternately, fiber optic techniques have been proposed for carrying data in automotive and similar systems. Fiber optic techniques, however, are generally very expensive with present technology.
It would be advantageous to provide a communication network that is immune to voltage transients and other electromagnetic interference of the type typically found in the automotive environment. It would be further advantageous to provide a communication network that is relatively simple and inexpensive as compared to prior art systems. It would also be advantageous to provide a communication network that will operate even if there is a break in the network cable. The present invention provides such a communication network.
Commonly assigned, copending application Serial No. 07/315,557, filed concurrently herewith and entitled "Alternate Pulse Inversion Encoding Scheme for Serial Data Transmission" discloses a data encoding and decoding method which may be advantageously used to transmit data over the communication network of the present invention, and that application is incorporated herein by reference.